1. Field of the Invention
The present invention relates to biliquid foams with a high alcohol content and to products which are formulated therefrom.
2. The Prior Art
Biliquid foams are known in the art in which small droplets of a non-polar liquid such as an oil are encapsulated in a surfactant-stabilized film of a hydrocarbon bonded liquid, such as water, and separated from one another by a thin film of the hydrogen bonded liquid. The water or other hydrogen bonded liquid thus forms the continuous phase in biliquid foam compositions.
U.S. Pat. No. 4,486,333 to Sebba discloses a method for the preparation of biliquid foam compositions which may comprise the non-polar liquid in a total amount of about 60% to about 98% by volume, the hydrogen bonded liquid constituting the balance. The polar liquid may comprise a petroleum derivative, paraffin or a liquid halogenated hydrocarbon. The biliquid foam composition prepared comprising 96% by volume methanol and 4% by volume water had a limited stability of only several days.
Biliquid foams are disclosed in the following literature references by Sebba:
“Biliquid Foams”, J. Colloid and Interface Science, 40 (1972) 468-474; and “The Behaviour of Minute Oil Droplets Encapsulated in a Water Film”, Colloid Polymer Sciences, 257 (1979) 392-396.
WO 97/32559 discloses a stable dispersion comprising an oil-based biliquid foam and an aqueous gel which is suitable for use in cosmetics, pharmaceuticals and other industries. This patent specification does not describe the use of high levels of alcohols in the compositions.
U.S. Pat. No. 4,999,198 disclosed a biliquid foam (or polyaphron) having a continuous aqueous phase and a disperse phase in which a drug is carried in the disperse phase. This patent does not disclose the use of alcohol in the aqueous phase.
There is a need to generate aqueous products with high levels of alcohol, in particular in the cosmetic and personal care markets. This need is not, however, addressed by conventional emulsion science because of the instability of emulsions containing high levels of alcohol in the aqueous phase. There is also a need to generate topical oil-based products with a high level of alcohol, which increases skin permeability, but which products do not suffer from the disadvantage of the resulting skin dryness.